Antihistamine and decongestants are used for the temporary relief of symptoms of the common cold, allergic rhinitis and sinusitis. The antihistamine brompheniramine and the decongestant pseudoephedrine are therapeutically indicated for recipients needing relief of these symptoms.
Brompheniramine is a propylamine derivative antihistamine. Brompheniramine is a racemic mixture of the dextro and levo isomers. Pharmacologic activity is predominantly due to the d-isomer. Dextrobrompheniramine, the dextro isomer, is approximately twice as active. Brompheniramine is administered for its effects as a therapeutically acceptable salt, preferably as brompheniramine maleate. Brompheniramine maleate occurs as a white crystalline powder, freely soluble in aqueous-type fluids, and it is absorbed from the gastrointestinal tract.
Pseudoephedrine is a sympathomimetic drug which occurs naturally in plants of the Ephedra. Pseudoephedrine is a stereoisomer of ephedrine. Pseudoephedrine is administered for its beneficial effects as a therapeutically acceptable salt, preferably as the hydrochloride or the sulfate. Pseudoephedrine hydrochloride occurs as a fine, white crystal or powder, it is very soluble in aqueous-type fluids, and it is absorbed from the gastrointestinal tract.
It would be desirable to provide a pharmaceutical dosage form comprising the two different drugs that are initially delivered in a therapeutically effective amount, followed by delivery of the drugs at a controlled rate, and for a time period, established to meet a specific therapeutic need. That is, it would be desirable to provide a dosage form that comprises an exterior lamina comprising pseudoephedrine and brompheniramine and a releasable binder, which lamina delivers both drugs immediately for substantially eliminating the start-up time of the dosage form and for providing immediate therapy to a recipient. The exterior drug-containing lamina for delivering an initial drug-pulse acts in cooperation with the dosage form that follows with the drugs then delivered at a controlled rate over time.
Additionally, it would be desirable to provide a pharmaceutical dosage form comprising the two different drugs for their simultaneous administration for obtaining the physiological and pharmacological benefits of each drug. Such a novel dosage form can be used for the desired medical relief where each individual drug addresses different symptoms of the particular medical situation. Prior to this invention, however, the coadministration of these drugs in a predetermined ratio did not appear feasible. For example, pseudoephedrine and brompheniramine appear kinetically incompatible in a pharmaceutical osmotically-controlled dosage form for their respective administrations within prescribed ratios because of their individual osmotic properties and their solubilities. Additionally, it is unobvious from their pharmacokinetic properties that pseudoephedrine and brompheniramine can be coadministered from a dosage form to the body at rates that are individually selected to achieve each of their separate therapeutic plasma concentrations.
Thus, in the light of the above presentation, it will be appreciated by those versed in the dispensing art, that if a novel and unique dosage form is made available for first, administering a pulsed amount of pseudoephedrine and brompheniramine and secondly, making available a means for housing the pseudophedrine and brompheniramine for their administration at a controlled and continuous rate in therapeutically effective ratios for obtaining the benefits of each drug, such a dosage form would have a definite use and be a valuable contribution to the dispensing art.